Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. One example routing solution to LLN challenges is a protocol called Routing Protocol for LLNs or “RPL,” which is a distance vector routing protocol that builds a Destination Oriented Directed Acyclic Graph (DODAG) in addition to a set of features to bound the control traffic, support local (and slow) repair, etc. The RPL architecture provides a flexible method by which each node performs DODAG discovery, construction, and maintenance.
One problem that confronts LLNs is scalability of the networks, since DAGs can be relatively small (e.g., hundreds of nodes) or extremely large (e.g., millions of nodes). Currently, scalability is achieved in RPL by limiting control plane traffic using dynamic timers (known as Trickle-based timers) to only require control plane traffic when needed, along with other mechanisms, such as threshold-based reporting (e.g., metric smoothing). Still, however, even with limited control plane traffic, many operations require action by the entire DAG, such as a complete rebuild of the DAG (global repair), which is an expensive operation for such networks. In addition, some of these actions in certain networks, such as those meant to carry sensitive traffic (e.g., alarms), may require frequent global operations. With large DAGs, complete rebuilds or other such operations are difficult to scale and can become extremely costly in terms of management (memory, processing, battery life, etc.).